[Doug]

Hey Ethic,

Chords don't have to be root, third, fifth although it sounds most stable when it's like that. You'll find that a lot of "standard" chord shapes on the guitar are actually inverted chords. So, for example, an open C played with all the strings is actually E C E G C E. So with an E in the bass, it's a first inversion - sort of (a real first inversion would be E G C).
Slash chords "should" denote inversions of a chord - the bass note of an slash chord "should" be a note within the makeup of the chord. Otherwise the chord is spelled wrong. For example a C/B should be spelled Cmaj7/B. But when you look up tabs on the internet, you'll find all kinds of differing levels of accuracy and quality.